High speed distribution of data for control of ultrasound devices

ABSTRACT

A method of distributing data to a transducer array of an ultrasonic device, the transducer array including transduction elements arranged in module units, includes generating a data packet using an optical transceiver controlled by a controller, the data packet including activation instructions encoded in a first wavelength, transmitting the data packet from the controller to a target device via a signal in an optical fiber, the target device having a beam divider device, splitting the data signal, using the beam divider device, into a plurality of data streams, where each of the data streams carries the data packet in an identical phase, transmitting the data streams to the module units, and activating the transduction elements based on the received data streams.

BACKGROUND

In typical imaging and therapy devices there are multiple individualtransducers, sub arrays, or elements. Individual transducers can beturned on or off at different times. When many transducers are operatedat the same time (as is typical with HIFU or imaging) the amount of datathat has to be transported to and from the transducers is significantand high speed transportation methods need to be used to distribute thedata. Typically, data distribution methods rely on utilizing copper orother conductors to transmit data.

In addition to the large amount of data that has to be delivered, stricttiming requirements must be met, particularly when the frequency ofoperation is in the MHz region and there are 10's or more of phasesteps. In such situations most conventional methods of data delivery areproblematic. Multiple individual conductors can be used to deliver thedata and synchronization pulses, however this can lead to an unwieldycable bundle making use and operation of the device challenging.

BRIEF SUMMARY

According to an embodiment of the disclosed subject matter, a method ofdistributing data to a transducer array of an ultrasonic device, thetransducer array including drivers to control groups of transductionelements arranged in modules, includes generating a data packet from anoptical transceiver in a controller, the data packet includingactivation instructions encoded in a first wavelength, transmitting thedata packet from the controller to a target device via a data signal inan optical fiber, the target device having a beam divider device,splitting the data signal, using the beam divider device, into aplurality of data streams, with each of the data streams carrying thedata packet in an identical phase, transmitting the data streams to thedrivers, and activating the transduction elements based on the receiveddata streams.

According to another embodiment of the disclosed subject matter, anultrasonic system includes a controller having a memory, an opticaltransceiver, and a processor that controls the optical transceiver togenerate a data packet that includes activation instructions encoded ina first wavelength, and a target device comprising an transducer arrayand a beam divider device connected to the optical transceiver by anoptical fiber, the transducer array having drivers that controltransduction elements of the transducer array. The controller transmitsa data packet to the target device in a data signal via the opticalfiber, the beam divider device splits the data signal into a pluralityof data streams and transmits the data streams to the drivers, and thedrivers activate the transduction elements based on the received datastreams.

Additional features, advantages, and embodiments of the disclosedsubject matter may be set forth or apparent from consideration of thefollowing detailed description, drawings, and claims. Moreover, it is tobe understood that both the foregoing summary and the following detaileddescription are illustrative and are intended to provide furtherexplanation without limiting the scope of the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the disclosed subject matter, are incorporated in andconstitute a part of this specification. The drawings also illustrateembodiments of the disclosed subject matter and together with thedetailed description serve to explain the principles of embodiments ofthe disclosed subject matter. No attempt is made to show structuraldetails in more detail than may be necessary for a fundamentalunderstanding of the disclosed subject matter and various ways in whichit may be practiced.

FIG. 1 shows a high speed data distribution ultrasound system accordingto an embodiment of the disclosed subject matter.

FIG. 2 shows a block diagram of a controller according to an embodimentof the disclosed subject matter.

FIG. 3 shows a block diagram of a target device according to anembodiment of the disclosed subject matter.

FIG. 4 shows an example flowchart of operation for an ultrasound systemaccording to an embodiment of the disclosed subject matter.

DETAILED DESCRIPTION

Various aspects or features of this disclosure are described withreference to the drawings, wherein like reference numerals are used torefer to like elements throughout. In this specification, numerousdetails are set forth in order to provide a thorough understanding ofthis disclosure. It should be understood, however, that certain aspectsof disclosure may be practiced without these specific details, or withother methods, components, materials, etc. In other instances,well-known structures and devices are shown in block diagram form tofacilitate describing the subject disclosure.

While, for purposes of simplicity of explanation, the methodologies areshown and described as a series of operations within the context ofvarious flowcharts, it is to be understood and appreciated that inembodiments of the disclosure some operations may occur in differentorders and/or concurrently with other operations from that shown anddescribed herein. Moreover, not all illustrated operations may berequired to implement a methodology in accordance with the disclosedsubject matter.

Devices and methods are disclosed for instruction, clock andsynchronization data distribution to an ultrasonic transducer arraydevice in a system that enables high speed operation with the devicebeing operated at some distance from a controlling computer. Thedisclosed methods and systems yield improvements in speed, size, andcontrol compared to conventional systems.

In operations of an ultrasonic applicator, such as those used in imagingor therapy treatments (e.g., Low Intensity Focused Ultrasound (LIFU) orHigh Intensity Focused Ultrasound (HIFU)), control information must bedistributed to multiple transduction devices. Any difference in arrivaltime of signals, for example, due to variations in physical distancebetween the receiving device and the source, can cause malfunction.

Multiple signal lines may be used to improve signal arrival time.However, minimizing the number of signal lines is beneficial forreducing complexity, size, and cost in practical systems. Moreover, inuse cases where the applicator is to be placed in a Magnetic ResonanceImaging system (MRI), most conductive elements must be kept below 15 cmin length. As such, the requirement to place the applicator in the MRIpresents challenges to the distribution of high speed data to thedevices. Thus, the need to distribute control information is challengingif it has to be done in pseudo real-time.

An ultrasonic imager or therapeutic device includes multiple individualtransducers. Individual transducers can be activated at different timesin accordance with a signal, such as continuous-wave (CW) at a chosenfrequency, pulse wave (PW), chirps, Gaussian, uni-polar or bi-polarpulses, square waves with two or more levels, or a signal of arbitraryfrequency content. Predictable and consistent arrival of such activationsignals at the individual transduction elements is critical to theperformance of the system. In the disclosed embodiments, a reducedcomplexity implementation to achieve consistent activation signals caninclude a single fiber activating a level shifter to drive a singleelement. Greater control and precision can be achieved by implementing amodular approach, where by some amount of digital control logic receivesa datagram and activates multiple elements at the correct time, phase,or clock ticks+phase when phase >360° for large arrays.

For example, in a CW system, transducers all operate at the samefrequency, but the phases between transducers may be different. A phasedifference as few as two phase steps, 0°/360° or 180° or more may bepresent depending on the application. The upper limit to the number ofphases is normally determined by the cost and complexity of the system,but even in a hypothetically powerful system at some level the phasedifference of any two nearby levels approaches or falls below the timinguncertainty such that further increase in the number of phases has noeffect on performance. Thus, precision of information arrival timelimits performance and accuracy of any ultrasonic transducer arraysystem in this regard. In other implementations where low numbers ofultrasound pulses are sent out there may be a need to activate elementsprecisely some number of cycles after first-activated elementseffectively phase shifts >360°

Generally, in these systems data needs to be passed from a controllingsystem (computer, microprocessor, FPGA, or ASIC) to target transducerdrivers. The drivers may be simple level shifters that amplify incomingdata to a level appropriate to drive a transducer, or they may becomplex circuits that generate the target signal internally and thenamplify that signal or cause the signal to be manifested in thetransducer (e.g., PWM synthesis), or they may be further configured togenerate signals for multiple elements.

Transducer drivers may also have low noise amplifiers andanalog-to-digital converters (ADCs) that allow the transducer to convertincoming pressure waves to electrical signals suitable for signalprocessing and analysis. This data typically is transmitted back to thecontrolling system for further analysis, imaging, or feedback purposes.Limited numbers of signal conductors, or signal conductors with lowbandwidth, may limit the quantity of data returned. Simplerimplementations may simply amplify the signal and send it back to thecontrolling computer for digitization and analysis.

The disclosed system distributes control information and synchronizationpulses to multiple transducer modules via a light guide, for example,implemented in the form of an optical fiber. The light guide can bedesigned to distribute the same data signal to all modules with no phasechange in the signal. The light guide can conversely be used as anaggregator of data transmitted back from the modules, thus reducing theburden on the cable to the applicator.

FIG. 1 shows a high speed data distribution ultrasound system 100according to the disclosed embodiments. A controller 110 (e.g., acomputer) is connected to a target device 120 (e.g., an ultrasoundprobe) via an optical fiber 130. The controller 110 uses an opticalsignal to send instructions to the target device 120 through the opticalfiber 130.

FIG. 2 is a block diagram of an embodiment of the controller 110. Thedepicted embodiment includes a bus 21 that interconnects majorcomponents of the controller 110. Such components may include a centralprocessor 24; a memory 27, such as Random Access Memory (RAM), Read OnlyMemory (ROM), flash RAM, or the like; an optical transceiver 28,connected to the optical fiber 130; a user display 22, such as a displayscreen; a user input interface 26, which may include one or more userinput devices such as a touchscreen implemented on display 22, or akeyboard, mouse, keypad, touch pad, turn-wheel, or the like; a fixedstorage 23 such as a hard drive, flash storage, or the like; a removablemedia component 25 operable to control and receive a solid-state memorydevice, an optical disk, a flash drive, or the like; a network interface29 operable to communicate with one or more remote devices via asuitable network connection; and a speaker 30 to output an audiblecommunication to the user. In some embodiments the user input interface26 and the user display 22 may be combined, such as in the form of atouch screen.

The bus 21 allows data communication between the central processor 24and one or more memory components 25, 27, which may include RAM, ROM,and other memory, as previously noted. Applications, instructions anddata resident with the controller 110 are generally stored on andaccessed via a computer readable storage medium.

The network interface 29 may provide a direct connection to a remoteserver via a wired or wireless connection. The network interface 29 mayprovide such connection using any suitable technique and protocol, aswill be readily understood by one of skill in the art, including digitalcellular telephone, WiFi, Bluetooth®, near-field, or the like.

FIG. 3 is a block diagram of an embodiment of a target device 120. Thetarget device 120 includes a beam divider 140 and a transducer array150. The beam divider 140 receives data from the optical fiber 130 anddivides the signal into a plurality of data streams 160, which channelsthe data to the transducer array 150. The beam divider 140 can includeone or more beam splitters for dividing a signal traveling from thecontroller 110 to the target device 120, and one or more beam combinersfor combining signals received from the transducer array 150 to betransmitted back to the controller 110.

When the data signal is divided into data stream carriers 160 (e.g.optical fibers), each individual data stream carrier 160 transmitsidentical data in an identical phase. That is, as the beam divider 140divides the optical power it does not affect the phase of the signalstraveling down it. Since the speed of transmission is much faster in theoptical fiber than the speed in electrical conductors, any changes inphase of the data due to differences in length of the data streamcarriers 160 is minimal for the typical frequency of operation oftransducers (<20 MHz). In fact, implementations of the disclosed subjectmatter can achieve division of data streams with essentially 0 phaseshift by using data stream carriers 160 implemented with optical fibershaving the same length, thereby improving the accuracy and precision ofthe device.

The data stream carriers 160 transmit a data stream to driver circuits170 in the transducer array 150. In the disclosed embodiments thedrivers 170 received the same data from the data stream carriers 160 atsubstantially the same point in time. The data can include a clocksignal and instructions to individual transduction elements 180 (e.g.,piezoelectric transduction element). As will be discussed further below,the instructions can include an address and a command, for example, atrigger command that causes the elements 180 to activate and emit anultrasonic pulse.

In one embodiment, the transduction elements 180 are assigned to modules190, where each module 190 includes a set number of elements 180 thatare all controlled by a driver circuit 170. In one embodiment themodules 190 are each identical in size. In another embodiment themodules 190 differ in size. The modules 190 in FIG. 3 are depicteduniform in shape and spaced apart for the sake of clarity, however,modules 190 that are adjacent and of varying shape are within the scopeof this disclosure. In a simple implementation of a module 190, thedriver circuit receives an optical signal from the data stream drivers160 and drives a plurality of level shifters that drive the elements180. In another implementation an ASIC can receive a datagram from thedata stream drivers 160 that includes information about a number of Nelements and electronically activate the elements 180 based on the datain the datagram. Different configurations of driver circuits 170 inmodules 190 are possible.

The disclosed embodiments utilize a global address space implementedsuch that each driver circuit 170 can discriminate data destined forelements 180 within that driver's module 190. Each driver circuit 170scans the received data stream for addresses within its own space eitheron a per module 190 basis (e.g., ADDR:Module1_Element17) or on a perelement 180 basis (e.g. ADDR:Element1565, ADDR:Element1567, etc.). Theaddressing scheme can comprise a single ‘level’ for an address ormultiple ‘levels’ as the need varies depending upon the system orapplication. That is, some applications may use the same hardware,however, utilize a less demanding address structure.

The arrangement of the address order in the data stream can be adjustedaccording to the needs of the system 100. In one embodiment theaddresses are contiguous within the data stream, which can supportalgorithms for faster processing on the target device 120 side. Inanother embodiment the addresses are randomly distributed within thedata stream, which can allow for faster processing on the controller 110side in generating the data signal.

The mode of data transmission can be serial digital for relativelysimple transmission of data or to reduce processing requirement. Formore complex data or to increase the speed/efficiency of transmission,frequency or amplitude modulation (FM or AM) can be used. For example,in one embodiment amplitude modulation with a tracking decoder at thereception end is used to transmit the data stream.

In addition to element-by-element instructions, the controller 110 cantransmit a code in the data signal that passes global instructions tothe modules 190 via the data stream carriers 160. For example, the datastream carriers 160 can carry a command code for all elements 180 toactivate on a next clock signal, or for all elements 180 to turn off ona next clock signal, etc. A global code can further be used to achievesynchronization among the modules 190 by instructing the modules tosynchronize 190 at a given clock signal.

Regarding the clock signal, in order to provide precise performance, theclock signal must be simultaneously distributed so that all drivers 170operate on the same frequency. The clock should be phase synchronouswith the leading edge arriving at a same time on each driver circuit170. Depending on the system capabilities, this can be achieved indifferent ways. In some embodiments, as described above, the data streamitself can carry clock timing data. In other embodiments a dedicatedfiber cable (not shown) can be used to exclusively carry a clock timingsignal. In other embodiments the clock signal can be transmitted throughthe same optical cables as the data signal, but use afrequency/wavelength that differs from the frequency/wavelength used totransmit the data, utilizing specific filters at the beam divider 140 toseparate the clock signal from the data. The clock signal may also bedistributed in the form of a frequency modulation (FM) carrier oramplitude modulation (AM) carrier, the data would be modulatedappropriately atop the carrier (clock) signal. It would also be possibleto modulate the data on the carrier using phase modulation or othermodulation schemes such as quadrature amplitude modulation (QAM).

In some circumstances a dynamic response to a situation may require adistribution of an independent synchronization pulse, activation pulse,or clock pulse that is not embedded in the data signal. To execute adynamic response the optical transceiver 28 can transmit the requiredinformation by transmitting a light down the fiber cable 130 in awavelength that differs from the wavelength of light used for thedata/timing signal transmission, essentially creating a secondarychannel. The beam divider 140 can send a secondary signal to carry thatinformation. In some embodiments, the addition of a frequency selectivebeam splitter (not shown) at each module 190 allows the separation ofthe two data streams with relatively little to no phase change betweenthe modules 190. This technique can be extended to any number ofsignals, each with a different wavelength as required, creating multiplechannels.

Certain applications can require information be transmitted back throughthe optical fiber 130, for example, to provide feedback for performanceevaluation or when the target device 120 is an ultrasonic imager. Toaccomplish this, in one embodiment data from the transduction elementsis collected through an ordered response to an instruction to transmitdata on a per element basis (e.g., a polling algorithm executes to polleach element individually at each individual address in the transducerarray). This method allows control over the rate of data beingtransmitted back to the controller 110 from the target device 120. Inanother embodiment the elements 180 can simply be configured to transmitdata as it is generated in order to reduce the size, complexity and costof control electronics.

A star combiner (not shown) in the beam divider 140 can be used tocombine the data from the transduction elements into a single opticaldata signal. The amalgamated optical data signal can be transmitted backto the controller 110 via the optical fiber 130. If there isinsufficient bandwidth for a single wavelength of light, multiplewavelengths can be used to increase the bandwidth of the channel.

FIG. 4 shows an example flowchart 400 of operation for the disclosedultrasound system. As described above, the system includes a controllerthat controls a target device that operates a transducer array. Althoughthe process is described as a series of operations, a person of ordinaryskill in the art will recognize that other functional operations can beexecuted as part of the process as needed, for example, for practicalimplementation purposes.

At operation 410 the controller generates a data packet via an opticaltransceiver controlled by a processor. The data packet includesactivation instructions encoded in a first wavelength. The data packetcan also include a clock signal. The clock signal can be encoded using asecond wavelength different from the first wavelength.

At operation 420 the data packet is transmitted from the controller to atarget device via a signal in an optical fiber, the target device havinga beam divider device. At operation 430 the beam divider device splitsthe data signal into a plurality of data streams, each data streamcarrying the data packet in an identical phase. That is, splitting thedata signal occurs by dividing the data signal into two or more datastreams with a zero phase shift across the divide.

At operation 440 the data streams are transmitted to drivers of thetransducer array. The drivers can control individual transductionelements or control modules, where each module includes a plurality ofelements. Each driver simultaneously or substantially simultaneouslyreceives the same data in the same phase. The data can include, amongother information, activation instructions for the elements, globalinstructions for the array, and a clock signal. Each driver scans thedata received for activation instructions corresponding to addresses forone or more elements that the driver controls. The address format can bea direct element address or a module address with an element subaddress.

At operation 450 the drivers, having activation instructions and clocksignal data, activates the elements. The activation instructions caninclude a trigger instruction having a corresponding time based on theclock signal. In total the corresponding times of the triggerinstructions can vary across the array to introduce a delay and guide awavefront created by the activation of the elements. In this manner thecontroller can operate the array as a phased array. In the case wherethe drivers receive global instructions, e.g., activate on the nextclock signal, the drivers simultaneously execute the global instructionat each element in the array.

At operation 460 imaging data is received from elements in the array andcombined into a return data packet. The return packet can also includeadditional system maintenance data, such as a measure of supply voltageto the array, current consumed by elements, modules or ASICs,temperature, etc. The return data packet can be encoded using wavelengthor frequency that is different from the wavelength or frequency that wasused to encode the data packet containing instructions. For example, adata packet transmitted from the controller to the target device caninclude activation instructions encoded in a first wavelength while areturn data packet transmitted from the target device to the controllercan include imaging data encoded in a second wavelength different fromthe first wavelength.

At operation 470 the return data packet is transmitted back to thecontroller via the optical fiber. The return packet can be transmittedusing a third wavelength different from the first wavelength (used fororiginal data packet) and the second wavelength (used for the clocksignal).

The proposed system can be compatible with magnetic resonance imaging(MM) systems. For MR guided high intensity focused ultrasound (HIFU)treatments the array must be capable of functioning within the magnetbore so that MR imaging can be carried out during operation. To achievethis compatibility, magnetic materials must be excluded from the design,and a configuration should be utilized that minimizes or eliminatesconductor loops that carry current to prevent interference with the MRsensing.

The advantages of the disclosed embodiments are applicable to variousultrasonic imaging modalities, for example, continuous wave (CW),Doppler, B-mode, elastography, acoustic radiation force impulse (ARFI),plane wave imaging (PWI), etc., and in both high intensity focusedultrasound (HIFU) therapy and low intensity ultrasound therapy.

The disclosed system enables distribution of control data to multiplemodules with zero or near zero phase shift in the data between each limbof the system. Embedding clock and data together in the same data streamallows recovery of clock signal in different modules to be phasesynchronous with other modules. Furthermore, the system has thecapability to distribute a separate data channel with the first datachannel for timing or control, with no change in phasing betweenchannels and data for each distribution point.

Thus, the disclosed system and methods achieve an increase in phaseresolution beyond what is possible with other conventional ultrasoundsystems and methods. Other advantages include: 1) improved closed-loopoperation due to reduced delay between elements, components, and controlsystem, 2) improved imaging and therapy within an MR system due toreduced metal or other components, 3) improved performance witharbitrary location of transduction modules and increase in overallseparation, and 4) a reduction in a limit on number of phase levels thatcan be applied to an ultrasound system since the limiting factor is nowthe timing delays in the electronic circuits instead of the distributionof signals to those circuits.

The foregoing description, for purpose of explanation, has beendescribed with reference to specific embodiments. However, theillustrative discussions above are not intended to be exhaustive or tolimit embodiments of the disclosed subject matter to the precise formsdisclosed. Many modifications and variations are possible in view of theabove teachings. The embodiments were chosen and described in order toexplain the principles of embodiments of the disclosed subject matterand their practical applications, to thereby enable others skilled inthe art to utilize those embodiments as well as various embodiments withvarious modifications as may be suited to the particular usecontemplated.

1. A method of distributing data to a transducer array of an ultrasonicdevice, the transducer array including drivers to control groups oftransduction elements arranged in modules, the method comprising:generating a data packet from an optical transceiver in a controller,the data packet including activation instructions encoded in a firstwavelength; transmitting the data packet from the controller to a targetdevice via a data signal in an optical fiber, the target device having abeam divider device; splitting the data signal, using the beam dividerdevice, into a plurality of data streams, with each of the data streamscarrying the data packet in an identical phase; transmitting the datastreams to the drivers; and activating the transduction elements basedon the received data streams.
 2. The method of claim 1, wherein the datapacket includes a clock signal.
 3. The method of claim 2, wherein theclock signal is encoded using a second wavelength different from thefirst wavelength.
 4. The method of claim 2, wherein the clock signal isencoded as a carrier wave, such as FM or AM.
 5. The method of claim 4,wherein the carrier wave is one of frequency modulation (FM), amplitudemodulation (AM), or quadrature amplitude modulation (QAM).
 6. The methodof claim 1, wherein the data packet includes an activation instructionand corresponding address for each transduction element in thetransducer array.
 7. The method of claim 6, wherein the correspondingaddress comprises a module address and a transduction elementsubaddress.
 8. The method of claim 6, wherein the activation instructioncomprises a trigger instruction having a corresponding time based on theclock signal.
 9. The method of claim 8, wherein the corresponding timevaries across the transducer array to introduce a delay to guide awavefront created by the activation of the transduction elements. 10.The method of claim 1, wherein the data packet includes a globalinstruction that is executed by each transduction element in thetransducer array.
 11. The method of claim 1, further comprising:receiving imaging data from a plurality of transduction elements in thetransducer array; combining the imaging data into a return data packet;and transmitting the return data packet back to the controller from thetarget device via a return signal in the optical fiber.
 12. The methodof claim 11, wherein the return data packet is encoded using a secondwavelength different from the first wavelength.
 13. The method of claim1, wherein splitting the data signal comprises dividing the data signalinto two or more data streams with a zero phase shift across the divide.14. An ultrasonic system, comprising: a controller comprising a memory,an optical transceiver, and a processor that controls the opticaltransceiver to generate a data packet that includes activationinstructions encoded in a first wavelength; and a target devicecomprising a transducer array and a beam divider device connected to theoptical transceiver by an optical fiber, the transducer array havingdrivers that control transduction elements of the transducer array,wherein the controller transmits a data packet to the target device in adata signal via the optical fiber, the beam divider device divides thedata signal into a plurality of data streams and transmits the datastreams to the drivers, and the drivers activate the transductionelements based on the received data streams.
 15. The ultrasonic systemof claim 14, wherein the processor encodes a clock signal in the datapacket.
 16. The ultrasonic system of claim 15, wherein the processorencodes the clock signal using a second wavelength different from thefirst wavelength.
 17. The ultrasonic system of claim 14, wherein thedata packet includes an activation instruction and corresponding addressfor each transduction element in the transducer array.
 18. Theultrasonic system of claim 17, wherein each driver controls a moduleunit comprising a plurality of transduction elements, and thecorresponding address comprises a module address and a transductionelement subaddress.
 19. The ultrasonic system of claim 17, wherein theactivation instruction comprises a trigger instruction having acorresponding time according to the clock signal.
 20. The ultrasonicsystem of claim 19, wherein the corresponding time varies across thetransducer array to introduce a delay to guide a wavefront created bythe activation of the transduction elements.
 21. The ultrasonic systemof claim 14, wherein the data packet includes a global instruction thatis executed by each transduction element in the transducer array. 22.The ultrasonic system of claim 14, wherein: the transduction elementsgenerate imaging data, and the optical splitting device combines theimaging data into a return data packet and transmits the return datapacket to controller via a return signal in the optical fiber.
 23. Theultrasonic system of claim 14, wherein the beam divider device dividesthe data signal into a plurality of data streams by dividing the datasignal into two or more data streams with a zero phase shift across thedivide.